Recently, in order to provide stable services to smartphones or wireless devices (wireless terminals), installation of relay stations relaying communication between base stations and wireless terminals is in progress. Accordingly, it is possible to reduce ranges in which wireless terminals may not communicate with base stations due to influences of shadowing by obstacles such as buildings despite service zones.
Relay stations are not limited to relay stations installed to be fixed on buildings or towers, but can also be mounted on moving objects such as automobiles or trains on which people can get (for example, JP-A-2010-81435). Relay stations mounted on moving objects can maintain relative positional relations with wireless terminals and can communicate with base stations without adverse effects. Therefore, wireless terminals in moving objects can ensure stable communication.